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Undecidability of infinite post correspondence problemfor instances of size 8

Published online by Cambridge University Press:  22 June 2012

Jing Dong  and
Qinghui Liu
Jing Dong
Affiliation:
Dept. Comput. Sci., Beijing Institute of Technology, Beijing 100081, P.R. China. dongjing@bit.edu.cn; qhliu@bit.edu.cn
Qinghui Liu
Affiliation:
Dept. Comput. Sci., Beijing Institute of Technology, Beijing 100081, P.R. China. dongjing@bit.edu.cn; qhliu@bit.edu.cn
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Abstract

The infinite Post Correspondence Problem (ωPCP) was shown to be undecidable by Ruohonen (1985) in general. Blondel and Canterini [Theory Comput. Syst. 36 (2003) 231–245] showed that ωPCP is undecidable for domain alphabets of size 105, Halava and Harju [RAIRO–Theor. Inf. Appl. 40 (2006) 551–557] showed that ωPCP is undecidable for domain alphabets of size 9. By designing a special coding, we delete a letter from Halava and Harju’s construction. So we prove that ωPCP is undecidable for domain alphabets of size 8.

Keywords

ωPCPsemi-Thue systemundecidabletheory of computation

Information

Type
Research Article
Information
RAIRO - Theoretical Informatics and Applications , Volume 46 , Issue 3 , July 2012 , pp. 451 - 457
Copyright
© EDP Sciences 2012

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References

Références

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